1. Description of the Prior Art
Digital data processing arrangements to detect faults in data processing systems used in facilities that may be rendered unsafe by faulty data are known and, for example, disclosed in a magazine entitled "URTL-Circuit System U1 Having High Safeguard and Automatic Fault Diagnosis", SIEMENS ZEITSCHRIFT, 48th year, Vol. 7, July 1974, Pages 490 through 506.
In such systems, the process activating signals are switched off when a digital fault in data processing occurs. Devices are provided to recognize faulty data conditions and to cut off the operation before faulty control commands are rendered. In order to increase the availability of equipment, duplicate facilities are often provided. However, such duplicate facilities do not normally have the necessary safeguards to protect against the receipt of faulty data. Accordingly, such prior art systems, may still, lack proper fail-safe fault recognition equipment and hence may be a danger to people and equipment.
2. Field of the Invention
The field of art to which this invention pertains is fault recognition equipment and in particular to such equipment for use in connection with railroad safety devices.